A comparative study of structure, stability and ener- getic performance of 5,5 ′ -bitetrazole-1,1 ′ -diolate based energetic ionic salts: A future high energy density ma- terials B. Moses Abraham a , Vikas D. Ghule b and G. Vaitheeswaran a,c∗ Developing novel energetic materials of high detonation performance and low sensitivity is one of the primary objectives related to explosive research. By employing ab-initio calculations, a series of energetic ionic salts based on 5,5 ′ -bitetrazole-1,1 ′ -diolate (BTO) were thoroughly inves- tigated to understand the structure-property-performance interrelationship. The physicochemical and detonation characteristics of these energetic ionic salts including structural, electronic, vi- brational and performance parameters (heat of formation, detonation pressures, and detonation velocities) were discussed in detail. The strong intermolecular hydrogen bonding environment between the BTO 2− anion and various cations are mainly responsible for prominent detonation performance and enhanced molecular stability. Such strong intermolecular hydrogen bonds are observed in hydrazine and hydroxylammonium cation compared to other cations. To predict the accurate band gap, electronic band structures of the studied EIS were calculated using HSE06 hybrid functional and are found to be wide band gap insulator with a bandwidth ranging from 4.33- 5.05 eV. Careful inspection of various EIS revealed that the hydroxylammonium and hydrazine cations produce the highest density relative to other cations when combined with BTO anion. The detonation characteristics of BTO 2− are computed using EXPLO5 code. In particular, HA-BTO and TKX-50 exhibit high detonation pressure (38.85 and 40.23 GPa) and detonation velocities (9.94 and 9.91 km/s), superior to those of traditional nitrogen-rich energetic materials with mod- erate sensitivities. These results highlight the importance of hydrogen bonding interactions in designing energetic salts for the next-generation explosives, propellants, and pyrotechnics. 1 Introduction From gunpowder to modern explosives, the so-called age of en- ergetic materials enhanced the capability to design a variety of explosives that are widely used in both military and civilian appli- cations, such as aerospace science, weapons research, and mining engineering. With the continuing demand for advanced explo- sives, researchers are fascinated to design and synthesis materi- als with great power, good environmental compatibility, and high safety levels. However, until today, the controversial drama be- tween power and sensitivity placed a great challenge to develop a Advanced Centre of Research in High Energy Materials (ACRHEM), University of Hy- derabad, Prof. C. R. Rao Road, Gachibowli, Telangana, Hyderabad-500046, India. ∗ E-mail: vaithee@uohyd.ac.in b Department of Chemistry, National Institute of Technology, Kurukshetra, 136119 Haryana, India c School of Physics, University of Hyderabad, Prof. C. R. Rao Road, Gachibowli, Telan- gana, Hyderabad-500046, India. energetic materials with desired properties. For instance, ONC 1 and CL-20 2 have greater power than any other explosives, but their sensitivity and the presence of more nitro groups make the synthesis more strenuous and expensive. On the other hand, FOX- 7 3 is most insensitive explosive than the well-known TNT, but it contains only 70% of the heat of detonation than the commonly used HMX and RDX 4 . Therefore, the future high energy density materials (HEDMs) should be designed with ingenious strategies by focusing on the combination of chemistry, crystallography, and physics. Apart from metal-organic frameworks and energetic cocrys- tals, another emerging route to design powerful explosives is through the formulation of energetic ionic salts (EIS). The com- bination of unusual chemical structures and their inherent indi- vidual energetic properties yield a unique class of EIS with im- proved performance due to anion-cation interactions and dis- tinct crystal packing 5 . The most important parameter to create 1–16 | 1